This invention relates to movie equipment dollies for transporting movie or television filming apparatus, such as cameras, during filming.
Movie dollies are moveable hoist apparatus that are used in the film industry to support and move cameras and other equipment during film sequences. Known designs of dollies have lift arms, often hydraulically controlled, for adjusting camera elevation, a camera head assembly attached to the end of the lift arm for adjusting the pitch and roll orientation of a camera affixed to the arm and preferably four steerable wheels for translation of the dolly, when a film crew wants to move the camera during film sequences. Three types of dolly steering modes have been traditionally desired in the film industry and they are shown in FIGS. 1-3:
FIG. 1 shows the so-called crab steering mode, wherein the rolling or steering axes of the four steerable wheels are oriented in parallel. In the crab steering mode, the dolly moves generally laterally, as shown by the arrow in FIG. 1, the degree of lateral movement being controlled by the steering handle.
FIG. 2 shows the so-called circular steering mode, wherein the rolling or steering axes of the four steerable wheels are oriented to intersect at a common point, which establishes a circular turning radius. In the circular steering mode, the dolly translates in a circle, as indicated by the arrow in FIG. 2, with the diameter of the steering circle being controlled by the steering handle.
FIG. 3 shows the neutral steering mode, wherein the rolling axes of all four wheels are independently orientable and they are not steered by the steering handle. Rather, the wheels ride on a set of pre-laid tracks, similar to railroad tracks. In the neutral steering mode, the dolly wheels must be disengaged from the steering mechanism.
Previous dolly designs have accomplished all three desired steering modes by use of a transmission coupled to the steering mechanism and the steerable wheels, having selectable crab or circular steering modes, and means to disengage the steerable wheels from the steering system for the neutral mode. Known designs of movie dollies are described in U.S. Pat. Nos. 2,950,121; 3,022,901; 3,168,284; 4,109,678; 4,257,619; and 4,360,187.
Unfortunately, known movie dollies suffer from shortcomings that hamper efficient use by film crew personnel. Known camera levelling heads utilize three or more adjustment screw to orient pitch and roll of the movie camera relative to the lift arm, to level the camera. With three or more adjusting screws, a cameraman can not simultaneously adjust camera pitch and roll, which delays adjustment--a critical flaw during fast-moving action film sequences. Known levelling head designs are bulky, which increases dolly weight and height. Levelling head height restricts how low a camera can be oriented to the ground. Very low film shots cannot be attained with known levelling heads, unless they are attached to the lifting arm with an offset bracket.
Known movie dolly transmissions are bulky, heavy and have complicated designs encompassing inordinate numbers of moving parts that complicate transmission maintenance. It is desirable to manufacture lighter weight movie dollies than previous designs, to reduce the labor required to lift dollies, for example, from transport vehicles to outdoor filming locations. One effective way to reduce dolly weight is to decrease transmission weight and bulk. When shifting known dollies into or out of neutral steering mode, the film crew must perform one of two procedures. In one known design, a separate clutch mechanism, located on each wheel, must be disengaged in order to select the neutral steering mode and to get out of the neutral mode, each wheel must be separately indexed for reconnection to the steering system by manually aligning index marks on each wheel assembly and re-engaging the clutch mechanism. In a second known design, a pin is removed from each wheel assembly to select neutral steering, but to get out of the neutral mode, each wheel must be separately indexed for pin alignment before reinserting the pins. Both known designs require time-consuming manual realignment of the dolly wheels, in order to disengage the neutral steering mode.
Another shortcoming in known movie dolly construction is poor operator ergonomics. Steering, hydraulic lift actuation and transmission steering mode shifting on known dollies are performed on at least two separate control handles or are not accessible without removing at least one hand from the steering handle. The dolly operator normally prefers to keep both of his or her hands on the steering handle and if a rapid vertical camera height adjustment is needed while steering, the operator cannot maintain both hands on the steering handle. Rapid action sequences in many of today's popular films require maximum dolly operator efficiency.